Noise shield for acoustic devices



Dec. 11, 1945. E. L. ALFORD ETAL 2,390,488

NOISE SHIELD FOR ACOUSTIC DEVICES Filed Sept. 28, 1943 E. i. ALFQRD MEMO M L MART/N ATTORNEY Patented Dec. 11, 1945 NOISE SHIELD FOR ACOUSTIC DEVICES Edward L. Alford and Merlin L. Martin, Chatham, N. J., assignors to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application September 28, 1943, Serial No. 504,100

3 Claims.

This invention relates to noise shields for acoustic devices and more particularly to shield attachments for telephone transmitters especially suitable for use in locations of high ambient noise, for example in aircraft.

One object of this invention is to effectively shield the diaphragm of a telephone transmitter from external noise whereby the quality and intelligibility of speech transmitted are enhanced.

Another obiectof this invention is to improve the articulation obtainable with telephone transmitters in noisy locations.

A further object of this invention is to enable comfortable use through long periods of telephone transmitters-provided with noise shields adapted to engage the face of the user of the transmitter.

In one illustrative embodiment of this invention, a noise shield fora telephone transmitter comprises a body portion for mounting the transmitter and mouth and nosepiece portions havin edges contoured to fit closely the face of the user of the transmitter and thus form an acoustic seal thereat.

In accordance with one feature of this invention, the noise shield is formed to constitute individual nose and mouth cavities or chambers having communication through restricted apertures in a common wall therefor whereby the nasal cavity is included in the acoustic input system for the transmitter and good articulation is obtained.

In accordance with another feature of this invention, an elongated restricted passagewa is provided affording communication from the nose chamber to the atmosphere. This passageway facilitates comfortable breathing of the user of the telephone transmitter, attenuates noise waves so that their effect upon the transmission quality of the transmitter is very small and also provides a vent from the mouth chamber whereby the creation of deleterious pressures adjacent the transmitter diaphragm is prevented.

The invention and the above-noted and other features thereof will be understood more clearly and fully from the following detailed description with reference to the accompanying drawing in which:

Fig. 1 is a perspective view of a noise shield for a telephone transmitter, illustrative of one embodiment of this invention; and

Fig. 2 is a side sectional view of the noise shield shown in Fig. 1.

Referring now to the drawing, the noise shield illustrated is molded in one piece of soft rubber and comprises a body portion Ill having therein a cavity I i into which a telephone transmitter (not shown) may be snapped and having also a bore or passageway I2 for receiving the transmitter cord. The shield comprises also a flaring portion i3 having an internal wall H which divides the interior into a nose cavityor chamber i5 and a mouth cavity or chamber it, the two chambers having communication with each other by way of a pair of apertures ll in the wall ll, the two apertures i1 being equally spaced on opposite sides of the median longitudinal plane of the shield. Extending from the chamber i5 is an elongated, restricted passageway ill, the function of which will be pointed out hereinafter.

The edge [9 of the shield is contoured to conform to the face of the user, that is the upper portion, in Figs. 1 and 2, of this edge conforms to the bridge of the nose and adjacent portions of the face of the user and the lower portion conforms to the face surface about the mouth of the user, so that an acoustic seal is formed between the edge and the face. In some cases a soft edging, for example of chamois skin, may be secured to the edge iii to improve the acoustic seal.

In use, the shield is held against the face with the nose extending into the chamber l5 and the mouth extending into the chamber l6 and the edge portion 20 engaging the portion of the face between the nose and the upper lip. Thus, as will be apparent, both the nasal and mouth cavities are included in the acoustic input system for the transmitter and good articulation and high quality speech transmission are realized. The apertures i1 and passageway l8 facilitate breathing by the user and thus assure comfortable use of the transmitter over prolonged periods. As noted above, because of the configurat on of the edge IS, an acoustic seal is provided between the face of the user and the chambers i5 and i6 and, therefore. noise waves are excluded from the front ends of these chambers. The passageway l8, being elongated and of small cross-sectional area, affords a high impedance to noise waves ,so that noise is highly attenuated. The apertures i! also attenuate noise waves. Further, as is apparent, a relatively long path for noise waves,

as compared with the path for speech waves, is

provided. Consequently, the effect of noise waves upon the transmitter is minimized and highly intelligible transmission of speech in locations of high amb ent noise is attainable.

Although a specific embodiment of the invention has been shown and described, it will be understood that it is but illustrative and that various modifications may be made therein without departing from the scope and spirit of this invention as defined in the appende claims.

What is claimed is:

1. An attachment for a telephone transmitter, comprising a mouthpiece portion bounding a first cavity. a nosepiece portion bounding a second cavity. said cavities having communication with each other by way of an elongated restricted aperture, and means defining a restricted passageway connecting said second cavity to the atmosphere.

2. A noise shield for a telephone transmitter, comprising a body portion for receiving the transmitter, a flaring member extending from said body portion and having an edge contoured to fit the face of the user, said member having therein individual nose and mouth cavities in communication with each, other by wayot a path providing substantial attenuation oi noise waves, and means deiining a breathing vent having a high impedance to noise waves connectin the nose cavity to the atmosphere.

3. A noise shield for a telephone transmitter, comprising a pliant member including a portion for accommodating the transmitter, a flaring portion extending from said body portion and having an internal wall dividing the interior thereof into a nose cavity and a mouth cavity, said .wall having a restricted aperture therein and said tiaring portion having its edge remote from the body portion contoured to conform to the face or the user of the shield, and a portion defining an elongated restricted passageway extending from said first portion along said wall and connecting said nose cavity to the atmosphere.

' EDWARD L. ALFORD.

MERLIN L. MARTIN. 

